Magnetic sensors are widely used in many technical fields such as spatial location and orientation, automatic monitoring and control, and information storage. A magnetic sensing element in the magnetic sensor is a key part which determines performance and application of the magnetic sensor.
In principle, the magnetic sensing elements may be classified into different types such as a type of Faraday magnetic induction, a type of anisotropy magneto-resistance (AMR) effect, a type of Hall effect, a type of giant magneto-resistance (GMR) effect and a type of tunnel giant magneto-resistance (TMR) effect. The sensors based on GRM effect and the sensors based on TMR effect, due to their high sensitivity, are applicable to super-capacity information storage, and thus draw attention of those skilled in related fields all over the world. In recent years, to satisfy increasing requirement on storage density, development of magneto-resistance elements with ultrahigh sensitivity is in intense competition. The research and development focus on improving sensitivity and operation stability of the elements by finding more appropriate material, more appropriate multi-layer structure and more appropriate manufacturing process.
For conventional technologies, in WO/2012/093587 (CO2FE-BASED HEUSLER ALLOY AND SPINTRONIC DEVICE USING SAME), it is proposed that a CPP-GMR element with a maximum MR ratio and a high output signal is acquired by using Heusler alloy; in WO/2011/103437 (A HIGH GMR STRUCTURE WITH LOW DRIVE FIELDS), a multi-period structural element having ferromagnetic exchange coupling and exhibiting giant magneto resistance (GMR) is proposed; in WO/2011/007767 (METHOD FOR PRODUCING MAGNETORESISTIVE EFFECT ELEMENT, MAGNETIC SENSOR, ROTATION-ANGLE DETECTION DEVICE), a method for regulating magnetization orientation of a fixed ferromagnetic film and simplifying a preparation process of a GMR film is disclosed; in Application Number JP2009280406 (METHOD OF MANUFACTURING TMR READ HEAD, AND TMR LAMINATED BODY), a method for acquiring a TMR read head with a high MR ratio is disclosed; in Application Number JP2009202412 (TUNNEL JUNCTION TYPE MAGNETORESISTIVE HEAD AND METHOD OF MANUFACTURING THE SAME), it is disclosed a method for acquiring a TMR magnetic head with reduced deterioration in the MR ratio in a region in which area resistance RA is smaller than 1.0 Ωμm2; in WO/2008/142748 (MAGNETIC HEAD FOR MAGNETIC DISK APPARATUS), it is disclosed a read head including a TMR element or CPP-GMR element and having good signal transmission performance, which is applied to a hard disk drive (HDD) device; in WO/2010/050125 (CPP-GMR ELEMENT, TMR ELEMENT, AND MAGNETIC RECORDING/REPRODUCTION DEVICE), an L10Mn50Ir50 film having crystal magnetic anisotropy energy of 2×108 erg/cm3 is employed as an antiferromagnetic layer, which assures stability of the element for an astronomical number of 1.2×1049 years even if the element size is 5 nm.
Though the sensors based on GMR or TMR effect can satisfy recent development requirement on storage density technology at present, the sensor elements of the two types both have a multi-layer structure formed by superposing films having different performances (for example, see patents WO/2010/050125; WO/2002/078021; Application Number EP2006000077; Application Number EP2010011433), which has a special requirement on performance of film material, and causes a complicated preparation process for the element. In addition, the size of the magnetic head is required to be further reduced. Comprehensively limited to these key factors, difficulty in improving the performance of the element is increasing.
Hence, to address the above technical problems, research and development for the magnetic sensor element based on a new physical effect become a new direction of technical development in the field.